Silver halide emulsions sensitized with cyanine dyes containing a quaternary group

ABSTRACT

The present invention relates to photography and, more particularly, to a novel spectrally (optically) sensitized radiation recording photographic element which comprises a cyanine dye of the formula: WHEREIN L represents a methine group; m represents a positive integer of from 1 to 3, inclusive; Z and Z1 each represents the nonmetallic atoms necessary to complete a cyanine dye heterocyclic ring system containing a five or six membered heterocyclic nucleus; R and R1 each represents a divalent acylic cyclic group; X represents a quaternary ammonium, sulfonium or phosphonium group; Y represents a -SO3 or a -COO group; and W represents an anion.

United States Patent [191 v v 1 inn 3,7341739 Borror 1 May 22, 1 97 3 I1 SILVER HALIDE EMULSIONS FOREIGN PATENTS OR APPLICATIONS SENSITIZEDWITH CYANINE DYES O A NG A QUATERNARY 1,077,611 8/1967 Great Britain..96/ 137 GROUP Primary Examiner-J. Travis Brown [75] Inventor: Alan L.Borror, Arlington, Mass. AttorneyCharles Mikulka et al.

[73] Assignee: {Egg-(aid Corporation, Cambridge, I ABSTRACT [22] Filed:July 29, 1971 The present invention relates to photography and,

more particularly, to a novel spectrally (optically) sen- Sitizedradiation recording photographic element which comprises a cyanine dyeof the formula:

[21] Appl. No.: 167,500

[52] US. Cl. ..96/l32, 96/137, 96/140,

260/2404, 260/2406 ei hmm-c [51] int. Cl ..G03c 1/16, G030 1/18 [58]Field of Search ..96/l37, I24, 132; 260/2406 Jis I [56] References Citedwherein L represents a methine group; m represents a UNITED STATESPATENTS positive integer of from 1 to 3, inclusive; Z and Z,

each represents the nonmetallic atoms necessary to 2,256,163 9/ 1941Kumetat et al ..96/ 137 complete a cyanine dye heterocyclic ring systemcon- 2354524 7/ 1944 Kumetat at taining a five or six memberedheterocyclic nucleus; R 3,6l7,293 11/1971 Shiba et a1 ..96/l24 and R1each represents a divalent y i cyclic g p; X represents aquatemaryammonium, sulfonium or phosphonium group; Y- represents a -SOor a COO group; and W represents an anion.

l 1 Claims, No Drawings 1 SILVER I-IALIDE EMULSIONS SENSITIZED WITHCYANINE DYES CONTAINING A QUATERNARY GROUP BACKGROUND OF THEINVENTION 1. Field of the Invention The present invention is directed toproviding novel spectrally (optically) sensitized radiation recordingphotographic elements.

2. Description of the Prior Art In accordance with techniques disclosedin the prior art, photosensitive elements and particularlyphotosensitive silver halide elements may be provided with increasedelectromagnetic radiation absorption and photochemical response byspecified sensitization procedures. I

Among such procedures is found a technique categorized, and denoted, aschemical sensitization, wherein a photosensitive element, andparticularly a photosensitive silver halide element, may be treated withcompounds such as various sulfur compounds, for example, those set forthin U.S.Pat. Nos. 1,574,944; 1,623,499 and 2,410,689; salts of noblemetals such as ruthenium, rhodium, palladium, iridium and platinum, allof which belong to Group III of the Periodic Table of Elements and havean atomic weight greater than 100, for example, potassiumchloroplatinate, sodium chloropalladite, ammonium chlororhodinate, andthe like, in amounts below that which produces any substantial foginhibition, as described in U.S. Pat. No. 2,488,060; gold salts, forexample, potassium aurothiocyanate, potassium chloroaurate, aurictrichloride, and the like, as described in US. Pat. Nos. 2,597,856 and2,597,915; reducing agents such as stannous salts, for example, stannouschloride, as described in US. Pat. No. 2,487,850, individually or incombination. Such chemical sensitization procedures provide increasedresponse to electromagnetic radiation by the photoresponsive silverhalide treated over the frequency range of the inherent, or natural,response characteristics of the crystal.

A second procedure comprises a technique categorized, and denoted, as aspectral, or optical, sensitization procedure, wherein a photosensitivematerial, and particularly photosensitive silver halide, is providedfrequency-selective electromagnetic radiation response characteristicsand/or an increase in its inherent, or natural, spectral responsecharacteristics.

In general, such spectral sensitization procedures are accomplished bythe adsorption onto one or more surfaces of the photosensitive materialof one or more dyes selected from certain classes of dyes including,preferably, cyanine dyes and dyes related to them. For an extensivetreatment of cyanine dyes particularly adapted to provide spectralsensitization of, for example, a photosensitive silver halide crystalsee Hamer, F. M., The Cyanine Dyes and Related Compounds, lntersciencePublishers, New York, N.Y., U.S.A., (1964).

By means of the traditional procedures disclosed in the art as adaptedto accomplish spectral sensitization of photosensitive material, andpreferably sensitization of photosensitive silver halide, a cyanine dyein the form of polymeric aggregates is adsorbed to the receptive faces,or surfaces, of the photoresponsive material in a statisticalmonomolecular layer thickness or less.

Generally, the cyanine dyes preferably employed for purposes of spectralsensitization comprise an amidinium ion system in which both of thenitrogen atoms are included within separate heterocyclic ring systems,and in which the conjugated chain joining the nitrogen atoms passesthrough a portion of each heterocyclic ring merocyanine. Adsorption isgenerally believed to be partly accomplished by an unknown type ofchemiadsorption between negative crystal surface charges provided, for'example, by the excess halide components of the silver halide, and thepositive charge of the cyanine chromophore. Adsorption is also favoredby the ability to form silver complexes with nuclei containing anamidinium nitrogen atom of a selected cyanine dyes heterocyclic ringsystem, or systems, for example, with a nuclear sulfur, oxygen, orselenium atom, or a second nuclear nitrogen atom not directly acomponent of the amidinium ion system.

It has also been understood that the efficiency of the spectralsensitization of a, for example, silver halide crystal increases inaccordance with an increase in the chemiadsorption of the selectedsensitizing dye, in the form of polymeric aggregates, on the appropriatesurfaces, or faces, of the crystal up to the concentration at whichincrease of sensitivity peaks or plateaus. Specifically, maximumsensitization has been found ordinarily to occur at a dye concentrationlevel less than or equal to a statistical monomolecular layer of dyecoverage on the adsorbing surfaces of the crystal, usually just short ofmonomolecular coverage of the crystal surface.

Sensitivity conferred by a sensitizing dye thus does not increaseproportionately to the concentration of the dye, but rather passesthrough a maximum as concentration is increased. Attempts to increasethe spectral sensitivity of the crystal by increasing the concentrationof sensitizing dye adsorbed by its appropriate surfaces beyond theplateau or peak concentration level, provide a progressive decrease inspectral sensitivity as the concentration is so increased; see: Hamer,F. M., The Cyanine Dyes and Related Compounds, supra, and Borin, A. V.,Investigation of the Concentration Effect in Optical Sensitization ofPhotographic Emulsions, Uspekhi Nauch. Fab. Akad. Nauk. SSSR, Otdel.Ihim. Nauk. 7, 183-190 (1960). In many instances, this resultantdecrease in the crystals spectral sensitivity attains catastrophicproportions when the relative amount of dye necessary to provide a givenincremental increase in sensitivity, prior to attainment of the plateauor peak region, is compared with the same amount of dye, in excess ofthat which provides optimum sensitization.

The energy or charge-carrier absorptive propensity of a photoresponsiveelement comprising a particulate dispersion of photosensitive materialis generally dependent upon the effective, adsorbed presence ofsufficient dye to effect maximum absorption of, and transtionaloptically sensitized, photographic, photoresponsive elements, such aspanchromatic photographic emulsions, coated on a suitable supportingmember, comprising a relatively thin layer, for example, on the order ofabout 7 microns in thickness, and including a dispersion ofphotoresponsive silver halide in a gelatin matrix, for example, in aconcentration of about mgs. of silver per square foot, thephotoresponsive element only absorbs roughly in the order of less thanonethird of the available incident light, over the radiation frequencyrange desired for photographic employment of the element, with theconcomitant failure of such elements to even approximate theirpotential, or theoretica l, efficiency. The maximum absorbed radiationattributable to a given monomolecular dye layer adsorbed on aphotosensitive crystal is about 7 percent of the total incidentradiation. W. West and V. I. Saunders, Wissenschaftliche Photographie,W. Eichler, I-I. Frieser and O. I-Ielwich, eds., Verlag Dr. 0.I-Ielwich, Darmstadt, 1958, P. 48. The net response of the system thuscannot be improved by simply adding more of the same sensitizing dye,but must be achieved by development of more efficient and effectivesensitizing dye systems.

In US. Pat. Nos. 2,213,995 and 2,231,658 there is disclosed cyanine dyeswherein X of Formula I, infra, is a COOI-I group and Y is a -COO group;US. Pat. Nos. 2,503,776; 2,519,001; and 2,912,329, and British PatentNo. 742,1 12, German Patent No. 929,080, Belgian Patent No. 532,409disclose cyanine dyes wherein X* of Formula I is a SO H group and Y is aSO group; German Patent No. 1,028,718 discloses cyanine dyes wherein Xof Formula I is an alkyl group and Y is a OSO group; German Patent No.1,916,845 discloses cyanine dyes wherein X of Formula I is a -S-SO;,I-Igroup; and Y is a S--SO group; and US. Pat. Nos. 2,256,163 and 2,354,524disclose cyanine dyes wherein X* of Formula I is a N(alkyl);, group andY is an alkyl group.

SUMMARY OF THE INVENTION The present invention is directed to a novelspectrally (optically) sensitized radiation recording'photographicelement which comprises a cyanine dye of the formula:

wherein L represents a methine group; m represents a positive integer offrom 1 to 3, inclusive; Z and 2 each represents the nonmetallic atomsnecessary to complete a cyanine dye heterocyclic ring system containinga or 6 membered heterocyclic nucleus; R and R, each represents adivalent acylic or cyclic group; X represents a quaternary ammonium,sulfonium or phosphonium group; Y represents a SO or a -COO group; and Wrepresents an anion.

DETAILED DESCRIPTION OF THE INVENTION As previously characterized, thepresent invention is directed to a novel spectrally (optically)sensitized rudiation recording photographic element comprising a cyaninedye of Formula I, supra.

As examples of heterocyclic ring systems containing a 5 or 6 memberedheterocyclic nucleus contemplated for employment in the practice of thepresent invention, mention may be made of the traditional artrecognizedheterocyclic ring systems customarily employed as constituent componentsof cyanine dyes such as heterocyclic ring systems of the azole seriesincluding those of the thiadiazole and thiazole series, for example,thiazole; 4-methylthiazole; 4-phenylthiazole; S-methylthiazole;S-phenylthiazole; 4,5- dimethylthiazole; 4,5-diphenylthiazole;4-(2-thienyl)- thiazole; etc.; of the benzothiazole series, for example,

benzothiazole; 4-chloro-benzothiazole; S-chlorobenzothiazole;6-chloro-benzothiazole; 7-chlorobenzothiazole; 4-methyl-benzothiazole;S-methylbenzothiazole; 6-methyl-benzothiazole; 6-bromobenzothiazole;4-phenyl-benzothiazole; S-phenylbenzothiazole; 4-methoxy-benzothiazole;S-methoxybenzothiazole; 6-methoxy-benzothiazole; 5-iodobenzothiazole;6-iodo-benzothiazole; S-ethoxybenzothiazole; 6-ethoxy-benzothiazole;5,6-dimethoxybenzothiazole; S-hydroxy-benzothiazole;6-hydroxybenzothiazole; S-bromo-benzothiazole; 4-ethoxybenzothiazole;tetrahydro-benzothiazole; 5,6- dioxymethylene-benzothiazole; etc.; andof the naphthothiazole series, for example, a-naphthothiazole;B-naphthothiazole; [3,B-anphthothiazole; S-methoxy-B- naphthothiazole;5-ethoxy-B-naphtllothiazole; 7-methoxy-B-naphthothiazole;8-methoxy-anaphthothiazole; etc.; those of the selenazole series, forexample, 4-methylselenazole; 4-phenylselenazole; etc., including thoseof the benzoselenazole series, for example, benzoselenazole;5-chloro-benzoselenazole; 5- methoxy-benzoselenazole;5-hydroxy-benzoselenazole; tetrahydrobenzoselenazole; etc.; and of thenaphthoselenazole series, for example, B-naphthoselenazole;a-naphthoselenazole; etc.; those of the oxadiazole and oxazole series,for example, 5,methyloxazole; 4-pheny1- oxazole; 4,5-diphenyloxazole;4-methyloxazole; 5- phenyloxazole; 4,5-dimethyloxazole; etc., includingthose of the benzoxazole series, for example, benzoxazole;S-methylbenzoxazole; 6-methylbenzoxazole; 5,6-dimethylbenzoxazole;S-methoxybenzoxazole; 5- phenylbenzoxazole; S-carboxybenzoxazole; 5-sulfobenzoxazole; 5-chloro-benzoxazole; S-sulfomylbenzoxazole;6-dialkyl-amino-benzoxazole; 5- ethoxybenzoxazole; 6-methoxybenzoxazole;etc.; and of the naphthoxazole series, for example, 4,5-benzobenzoxazole; 5,6-benzobenzoxazole; 6,7- benzobenzoxazole; etc.; andthose of the imidazole series, for example, l-ethylimidazole',1-ethyl-4- phenylimidazole; 1-ethyl-4,S-dimethylimidazole; etc.; of thebenzimidazole series, for example, 5-chlorobenzimidazole;5,6-dichloro-benzimidazole; S-trifluoromethyl-benzimidazole;5-cyanobenzimidazole; S-carboxybenzimidazole; 5,6-dimethylbenzimidazole;etc.; and of the azine series including those of the pyridine seriessuch as of the Z-pyridine series, for example, pyridine;3-methylpyridine; 4-methylpyridine; 5- methylpyridine; 3,4-dimethylpyridine; 3 ,5 dimethylpyridine; 3,6-dimethyl-2pyridine;4,5-dimethyI-Z-pyridine; 4-chloro-2-pyridine; 5-chloro-2-pyridine;6-chloro-2-pyridine; 3-hydroxy-2-pyridine; 4-hydroxy- Z-pyridine;5-hydroxy-2-pyridine; 2-phenyl-2-pyridine; 6-phenyl-2-pyridinc; etc.; ofthe 4-pyridine series, for example, 2-methyl-4-pyridine;3methyl-4-pyridine; 2- chloro-4-pyridine; 3-chloro-4-pyridine;2,3-dimethyl-4- pyridine; 2-hydroxy-4-pyridine; 3-hydroxy-4-pyridine;etc.; of the pyrroline series; of the piperidine series; of thepyrimidine series; of the triazine series; of the thiazine series; ofthe thiazoline series, for example, thiazoline; 4-methyl-thiazoline;etc.; of the indolenine series such as of the 3,3-dialkyl-indolineseries, for example, 3,3-dimethyl-indolenine; etc.; and of the quinolineseries such as of the 2-quinoline series, for example, 2- quinoline;3-methyl-2-quinoline; 5-methyl-2-quinoline; 7-methyl-2-quinoline;6-chloro-2-quinoline; 8-chloro- Z-quinoline; 6-methoxy-2-quinoline;6-ethoxy-2- quinoline; 6-hydroxy-3-quinoline; 8-hydroxy-2- quinoline;etc.; and of the 4-quinoline series, for example, 4-quinoline;6-methoxy-4-quinoline; 6-methoxy-4- quinoline; 7-methyl-4-quinoline;8-methyl-4-quinoline;-

etc.

As will be recognized from the foregoing the heterocyclicnuclei setforth may readily comprise the various substituents known in the cyaninedye art as, for example, alkyl, halogen, alkoxy, hydroxy, aralkyl, aryl,acyl, amino, carboxamido, carbamyl, sulfonamido, sulfamyl, thio, cyano,heterocyclic, etc., substituents.

As examples of the anions, represented by the term W in the formulas setforth herein, contemplated for employment in the practice of the presentinvention mention may be made of the anionic acid anion radicalscustomarily employed in the cyanine dye art, such as, for example, Cl,Br, lClOf, H80 SO CH;, SO C H SO C H 'SO C H CH acetate, propionate,cyanate, etc.

As examples of the quaternary ammonium, sulfonium and phosphoriumgroups, represented by the term X in the formulas set forth herein,contemplated for employment in the practice of the present inventionmention may be made of CH3 C H3 wherein T is hydrogen, lower alkyl,lower alkoxy, halogen, etc.;

CH3 CzH5 As examples of the divalent acyclic and cyclic groups,represented by the terms R" and R," in the formulas set forth herein,contemplated for employment in the practice of the present inventionmention may be made of an alkylene or definically unsaturated straightor branched chain divalent aliphatic group preferably comprising up tofive carbon atoms such as, for example, methylene, ethylene, propylene,isopropylene, butylene, isobutylene, allylene, etc,, which may includesubstituents such as, for example, halogen Preferred cyanine dyes withinFormula I for employment in the practice of the present inventioncomprise a dye of the formula:

wherein Z and Z each represents the nonmetallic atoms necessary 'tocomplete a heterocyclic ring system containing a thiazole, selenazole,oxazole, imidazole or pyridine nucleus; R and R each represents adivalent aliphatic group comprising from one to five carbon atoms; Rrepresents an alkyl group comprising from one to five carbon atoms or anaromatic group comprising six nuclear carbon atoms; X represents a N (Rgroup wherein each R represents an alkyl group comprising from one tofour carbon atoms; Y- represents a SO or a COO group; and W representsan anion and particularly preferred dyes comprise those within theformula: Y

wherein V and V each represents oxygen, selenium; sulfur or wherein Rrepresents an alkyl group comprising from one to five carbon atoms; Zand 2,, each comprises the nonmetallic atoms necessary to complete anannulated benzene or naphthalene ring; R represents a hydrogen, methylor ethyl group; W represents an anion; R, and R each represents analkylene group comprising from one to five carbon atoms; X represents aN (R wherein each R represents an alkyl group comprising from one tofour carbon atoms; and Y represents 21 SO;,' or a COO group.

As examples of cyanine dyes within Formula I mention may be made of:

I (cu) m: (ca

| so fir(cu (s) r (CH2) 3 (ICHZ) 3 Br Mucu c1 T m Br ('r) s (cs -u tcn 31 2: I

cn-rn cu (CH3)2 The cyanine dyes of the present invention may beprepared by condensing a compound of the formula:

wherein R is an alkyl group, preferably comprising from one to threecarbon atoms and U is a R---X or R--Y group in the presence of a basewith a compound of the formula:

wherein R is a halo, alkylmercapto or arylmercapto group and U is --RY'when U is RX and U is RY when U is -RX to provide cyanine dyes ofFormula I wherein m is l and each 2 is the same or different;

condensing in the absence of a base a first quaternary salt of FormulaIV with an amidine such as N,N- diphenylformamidine or in the presenceof a base with the anhydride of a carboxylic acid, converting theproduct thereof to the thio analogue, alkylating the thio radical andcondensing the resultant product with a second quaternary salt ofFormula IV in the presence of a base wherein U is R-X when U of thefirst quaternary salt is RY and RY when U of the first quanternary saltis RX to provide cyanine dyes of Formula I wherein m is 2 and each Z isthe same or different; and

condensing in the absence of base a first quaternary salt of Formula IVwith a B-arylaminoacrolein anil salt and directly condensing the productthereof in the presence of a base with a second quaternary salt ofFormula IV as set forth immediately above to provide'a cyanine dye ofFormula I wherein m is 3 and each Z is the same or different.

The aforementioned base comprises a basic condensing agent such as anorganic amine, for example, tri-npropylamine, tri-n-butylamine,triisoamylamine, triethylamine, trimethylamine, dimethylaniline,diethylaniline, pyridine, N-alkyl-piperidine, etc., and most preferably'an organic tertiary amine having a dissociation constant greater thanpyridine (1 X an alkali metal carboxylate in a carboxylic anhydride, forexample, sodium acetate in acetic anhydride; etc.; or an alkali metalhydroxide, for example, sodium hydroxide, potassium hydroxide, etc.Preferably, the stated condensation reaction takes place in the presenceof heat and in a substantially inert reaction medium such as lowermolecular weight alcohol, for example, ethyl, npropyl, isopropyl,n-butyl or isobutyl alcohol or methoxy ethanol; tricresylphosphate; or aphenol; or a reaction medium itself comprising the condensing agent suchas pyridine.

As examples of the aforementioned carboxylic acid anhydrides, mentionmay be made of acetic anhydride, propionic anhydride, etc.

The quaternary salts of Formula IV may be readily prepared by condensinga compound of the formula:

with a halogenated sulfonic acid carboxylic acid, or a sultone such as2-bromoethane sulfonic acid, 3- bromopropionic acid, bromoacetic acid,4- bromobutyric acid, propane sultone, butane sultone, etc. to providequaternary salts of Formula IV wherein U or U is RY and withI-Ialogen-RX W wherein R represents hydrogen or an acyl group of acarboxylic acid such as, for example, acetyl, propionyl or benzoyl and Rrepresents an aryl group having six or 12 nuclear carbon atoms such asphenyl, diphenyl, xylyl, or naphthyl; or

condensing in the presence of base a quaternary salt of the formula:

with a quaternary salt of the formula:

IX IIz( l-( 7:

13 it jg As examples of the specific synthesis of cyanine dyes of theclass set forth in Formula I, for the purpose of illustration solely andnot intended to be limiting in any manner, the cyanine dye of Formula(A) may be prepared by dissolving l.6 grams of and 1.97 grams of CllaCIlain 200 cc.'of isopropanol; adding 2 cc. of triethylamine; stirringat 110 C. for 1 hour; cooling the mixture to room temperature; addingcc. of acetone to the mixture; and cooling the mixture in a refrigeratorovernight. The resultant crystalline product is removed by filtrationand extracted with isopropanol for l6 hours to provide 1.5 grams of thecyanine dye of Formula (A); X (in CH OH) 567 mu.

Elemental Analysis C H N 5 Calculated 51.94 6.25 5.52 13.87 Found 5l.746.ll 5.67 l3.92

The cyanine dye of Formula (F) may be prepared by dissolving 0.86 gramsof and 1.0 grams of the quaternary salt of Formula (2) in 15 cc. ofphenol; adding 1 cc. of triethylamine; stirring for 1 hour at 1 10 C.;cooling the mixture to room temperature; adding 50 cc. of acetone, andstirring at room temperature for 16 hours. The resultant crystallineproduct is removed by filtration, extracted with isopropanol for 16hours, and vacuum dried to provide 0.5 grams of the cyanine dye ofFormula (F); A (in CH OH) 575 mp.

The cyanine dye of Formula (G) may be prepared by dissolving 1.0 gramsof the quaternary salt of Formula (3) and 1.23 grams in 10 cc. ofphenol; adding 1 cc. of triethylamine; stirring at 1 10 C. for 2 hours;cooling the mixture to room temperature; and adding acetone. Theresultant crystalline product is removed by filtration, dissolved inmethanol, and ether added to provide a 53% yield of the cyanine dye ofFormula (G); A (in CH Ol-l) Elemental Analysis C H Calculated 54.15 5.378.75 Found 54.18 5.52 8.93

The cyanine dye of Formula (C) may be prepared by dissolving 1.0 gramsof COCH:

and 0.6 grams of N (CH:;):1-2 ll r- CH3 CH2. l

N+(CH3)3-2B1- in 20 cc. of isopropanol at reflux terripei'aturefafiing0.5 cc. of triethylamine, stirring at reflux temperature for 15 minutes.On cooling, the resultant crystalline product is removed by filtration,washed with isopropanol and vacuum dried to provide 0.6 grams of thecyanine dye of Formula (B); A,,,,,, (in Cl-l Ol-l) 567 mu.

Elemental Analysis C H N S Br Calculated 54.69 6.22 6.17 14.13 11.74Found 54.50 5.93 5.85 13.85 11.50

The cyanine dye of Formula (E) may be prepared by dissolving 1.1 gramsof and 1.3 grams of the quaternary salt of Forrriula (6) in 5 cc. ofpyridine at C. 0.3 grams of triethylamine is added and the solutionheated at C. forabout 2.5 hours. The cooled product mixture is pouredinto 350 cc. of a 5.1 acetone/ether mixture. 1.7 grams of crystallinecyanine dye of Formula (E) separated from the mixture and was purifiedby Soxhlet extraction with acetone for about 2 hours and vacuum dried at110 C. for 1 hour.

Elemental Analysis %C %H %N %S %Br Calculated 53.98 5.58 7.26 11.0813.18 Found 54.07 5.56 7.20 11.26 "12.60

Melting Point 300 C.

As examples of the preparation of illustrative quaternary salts of theclass set forth above in Formulas (l) to (8), the quaternary salt ofFormula (6) may be prepared by adding 60.3 grams of Br(Cl-I Br toprecooled 30 cc. of (CH N in a 250 cc. steel bomb, sealing the bomb,raising the temperature of the bomb to room temperature and allowing tostand for 72 hours. The solid product 77 grams of is triturated andwashed with ether until free ofreactants and dried in vacuo overDrierite at 60 C.

A mixture of 22.0 grams of -CH: \rq) and 40.0 grams of the reactant ofFormula (9) is heated at C. with vigorous stirring for 18 hours. Thesolid product broken up in ether and the resultant product isrecrystallized from a 1:3 C H OH/Cl-l 01-1 mixture, toprovide 29.0 gramsof the quaternary salt of Formula (6) M.P. l55-156 C.

The quaternary salt of Formula (1) may be prepared by heating awell-stirred mixture of 10.0 grams of CH3 OH: I I/ and 45 cc. ofpropionic anhydride at about 120 C. for 10 minutes. 15 cc. oftriethylamine is added over a pe riod of minutes followed by heating at120 C. for 45 minutes. The mixture is cooled and triturated in 300 cc.of. ethyl ether to provide 13.0 grams of the product which is dissolvedin 80 cc. of methanol, treated with 2 cc. of triethylamine, added to 200cc. of ethyl ether, and chilled to yield 10.3 grams of product M.P.156-l58 C.

A well-stirred mixture of 4.15 grams of the compound of Formula (12) and1.2 grams of P S in 75 cc. of Cl-lCl is refluxed for 2 hours, cooled toroom temperature, decanted. The solid is extracted with boiling CHCl andthe combined CHCl extracts evaporated to dryness to provide 4.5 grams ofthe product A well-stirred mixture of 4.5 grams of the compound ofFormula (13) and 5 cc. of methyl iodide in cc. of anhydrous methanol isallowed to stand at room temperature for 15 hours. The resultantprecipitate is removed by filtration, washed with methanol and dried toyield 1.9 grams of the quaternary salt of Formula (3) M.P. 267-270 C.

The preferred silver halide dispersions employed for the fabrication ofpreferred photographic film units comprising spectrally sensitizedphotoresponsive silver halide crystals, as specifically detailedimmediately above, may be prepared by reacting a water-soluble silversalt, such as silver nitrate, with at least one water soluble halide,such as ammonium, potassium or sodium bromide, preferably together witha corresponding iodide, in an aqueous solution of a peptizing agent suchas a colloidal gelatin solution; digesting the dispersion at an elevatedtemperature, to provide increased crystal growth; washing the resultantdispersion to remove undesirable reaction products and residualwater-soluble salts by chilling the dispersion, noodling the setdispersion, and washing the noodles with cold water, or, alternatively,employing any of the various flocc systems, or procedures, adapted toeffect removal of undesired components, for example, the proceduresdescribed in U.S. Pat. Nos. 2,614,928; 2,614,929; 2,728,662; and thelike; after-ripening the dispersion at an elevated temperature incombination with the addition of gelatin and/or such other polymericmaterials as may be desired and various adjuncts, for example, thepreviously detailed chemical sensitizing agents and the like; allaccording to the traditional procedures of the art, as described inNeblette, C. 8., Photography Its Materials and Processes, 6th Ed., 1962.

Optical sensitization of the dispersionss silver halide crystals maythen be accomplished by contact of the emulsion composition with aneffective concentration of the selected cyanine optical sensitizing dyeor dyes, each of which dyes has preferably been dissolved in anappropriate dispersing solvent such as methanol, ethanol, pyridine,acetone, water, and the like; all according to the traditionalprocedures set forth in the art such as, for example, the U. S. andforeign patents identified above. In general, the concentration ofsensitizing dye or dyes may be varied empirically in accordance with thecharacteristics of the particular photoresponsive material such as thesilver halide selected and the sensitizing effects desired which in theinstance of pre ferred silver iodobromide dispersions will ordinarilyfall within the range of about 0.05 to 5 grams per grams of silverhalide measured as silver.

Subsequent to spectral sensitization, any further desired additives,such as coating aids and the like, may be incorporated in the emulsionand the mixture coated and processed according to the conventionalprocedures known in the photographic emulsion manufacturing art.

Alternatively, an emulsion coating can be prepared and coated on asuitable support whereupon the coating may be sequentially immersed inthe respective solutions of cyanine dyes.

Specifically, a gelatino silver iodobromide emulsion prepared asdetailed above and comprising a gelatin/silver ratio of about 1:1 andabout 4 mole percent bromide concentration may be chemically sensitizedwith gold and sulfur as, for example, by the addition, at about 56 C.,pH 5 and pAg 9, of a optimally sensitizing amount of a solutioncomprising 0.1 gram of ammonium thiocyanate in 9.9 cc. of water and 1.2cc. of a solution containing 0.097 grams of gold chloride in 9.9 cc. ofwater, and a 0.02 percent aqueous sodium thiosulfate solution.

The formulation may be optically sensitized in accordance with thepresent invention by the addition of a sensitizing concentration of oneor more of the cyanine optical sensitizing dyes detailed above as, forexample, 1, 2 and 4 mgs. per gram of silver of the cyanine dye ofFormula (A) dissolved in methanol.

The optically sensitized formulation may then be coated on anappropriate support as, for example, cellulose triacetate film base andthe film units thus prepared exposed in a conventional wedgespectrograph.

Upon processing with a photographic developing composition as, forexample, a conventional processing composition of the type commerciallydistributed by Eastman Kodak Company, Rochester, New York, U.S.A., underthe trade name of Dektol Developer" and comprising an aqueous alkalinesolution of monomethylpara-amino phenol sulfate and hydroquinone, and aconventional acid stop bath, the resultant spectrograms will detail thesensitivity characteristics of the optically sensitized formulationwhich may be directly compared with a nonoptically sensitized film unitor film units optically sensitized with selected prior art dyes.

'- It has been specifically found that in general preferred mesoalkyl(methyl, ethyl, etc.) substituted carbocyanine dyes of the presentinvention unexpectedly exhibit considerably higher extinctioncoefficients, e.g.,' in the range of about 150,000 to 200,000, than thecorresponding 3,3'-dialkyl, quaternary ammonium, sulfo or carboxysubstituted carbocyanine dyes of the prior art and that the preferreddyes exhibit a bathochromic spectral absorption shift in the A,,,,,, ofabout mp. in solution. In addition, the dyes of the present inventionhave been further found to possess increased solubility in water ascompared with corresponding prior art materials and thus there isfacilitated direct disposition of the such dyes in photoresponsivecompositions with concomitant decreased employment of, if not theabsence of, photographically deleterious organic solvent adjuvants suchas methanol and the like traditionally employed to effect disposition ofcyanine optical sensitizing dyes.

As previously detailed, the photoresponsive crystals of the presentinvention may be employed as the photosensitive component of aphotographic emulsion by incorporating within a suitable binder and thecoating and processing of the thus prepared emulsion according toconventional procedures known in the photographic manufacturing art.

The photoresponsive crystal material of the photo graphic emulsion will,as previously described, preferably comprise a crystal of a silvercompound, for example, one or more of the silver halides such as silverchloride, silver iodide, silver bromide, or mixed silver halides such assilver chlorobromide, silver iodobromide or silver iodochlorobromide ofvarying halide ratios and varying silver concentrations. The formulatedphotographic emulsions may be used for the preparation oforthochromatic, panchromatic and infrared sensitive photographic films.

The fabricated emulsion may be coated onto various types of rigid orflexible supports, for example, glass, paper, metal, polymeric films ofboth the synthetic types and those derived from naturally occurringproducts, etc. Especially suitable materials include paper; aluminum;polymethacrylic acid, methyl and ethyl esters; vinyl chloride polymers;polyvinyl acetals; polyamides such as nylon; polyesters such as thepolymeric films derived from ethylene glycol terephthalic acid;polymeric cellulose derivatives such as cellulose acetate, triacetate,nitrate, propionate, butyrate, acetatebutyrate, or acetate-propionate;polycarbonates; polystyrenes, etc.

The emulsions may include the various adjuncts, or addenda, according tothe techniques disclosed in the art, such as speed increasing compoundsof the quaternary ammonium type, as described in U.S. Pat. Nos.2,271,623; 2,288,226; and 2,334,864; or of the polyethyleneglycol type,as described in U.S. Pat. No.'

2,772,164; and those disclosed by Burr in fWiss. Phot., Volume 47, 1952,pages 2-28; the disulfides of Belgian Pat. No. 569,317; thebenzothiazolium compounds of U.S. Pat. Nos. 2,131,038 and 2,694,716; thezinc and cadmium salts of U.S. Pat. No. 2,839,405; and the mercaptocompounds of U.S. Pat. No. 2,819,965. Hardening agents such as inorganicagents providing polyvalent metallic atoms, specifically polyvalentaluminum or chromium ions, for example, potash alum and inorganic agentsof the aldehyde type, such as formaldehyde, glyoxal, mucochloric acid,etc; the detone type such as diacetyl; the quinone type; and thespecific agents described in U.S. Pat. Nos. 2,080,019; 2,725,294;2,725,295 2,725,305; 2,726,162; 2,732316;"2,950,197;fid 2,8 70,013, maybe incorpo rated in the emulsion.

The emulsion'may also contain one or more coating aids such as saponin;a polyethyleneglycol of U.S. Pat. No. 2,831,766; a polyethyleneglycolether of U.S. Pat. No. 2,719,087; a taurine of U.S. Pat. No. 2,739,891;a maleopimarate of U.S. Pat. No. 2,823,123; an amino acid of U.S. Pat.No. 3,038,804; a sulfosuccinamate of U.S. Pat. No. 2,992,108; or apolyether of U.S. Pat. No. 2,600,831; or a gelatin plasticizer such asglycerin; a dihydroxyalkane of U.S. Pat. No. 2,960,404; a bisglycolicacid ester of U.S. Pat. No. 2,904,434; a succinate of U.S. Pat. No.2,940,854; or a polymeric hydrosol of U.S. Pat. No. 2,852,386.

As the binder for photosensitive crystals, the aforementioned gelatinmay be, in whole or in part, replaced with some other colloidal materialsuch as albumin, casein; or zein; or resins such as cellulosederivatives and vinyl polymers such as described in an extensivemultiplicity of readily available U.S. and foreign patents.

The photographic emulsions may be employed in black-and-white or colorphotographic systems, of both the additive and subtractive types, forexample, those described in Photography, Its Materials and Processes,

supra. The photoresponsive crystals may also be employed in thefabrication of photographic emulsions which form latent imagespredominantly on the surface of the crystal or in emulsions which fonnlatent images predominantly inside the crystal such as those describedin U.S. Pat. No. 2,592,250.

The fabricated emulsions may also be employed in silver diffusiontransfer processes of the types set forth in U.S. Pat. Nos. 2,352,014;2,500,421; 2,543,181;

3,091,530; 3,108,001 and 3,113,866; in additive color diffusion transferprocesses of the types disclosed in U.S. Pat. Nos. 2,614,926; 2,726,154;2,944,894; 2,992,103 and 3,087,815; and in subtractive color diffusiontransfer processes of the types disclosed in U.S. Pat. Nos. 2,559,643;2,600,996; 2,614,925; 2,647,049; 2,661,293; 2,698,244; 2,698,798;2,774,668;

3,576,625 and 3,576,626; etc.

The photoresponsive crystals of the present invention may also beemployed as the photosensitive component of information recordingelements which employ the distribution of a dispersion of relativelydiscrete photoresponsive crystal, substantially free from interstitialbinding agents, on a supporting member such as those previouslydesignated, to provide image recording elements, for example, asdescribed in U.S. Pat. Nos. 2,945,771; 3,142,566; 3,142,567; Newman,Comment on Non-gelatin Film, B.J.O.P., 534, Sept. 15, 1961; and BelgianPatents Nos. 642,557 and 642,558.

As taught in the art, the concentration of silver halide crystalsforming a photographic emulsion and the relative structural parametersof the emulsion layer, for example, the relative thickness, and thelike, may be varied extensively and drastically, depending upon thespecific photographic system desired and the ultimate employment of theselective photographic system.

In conventional photographic processes, for the formation of silverimages, a latent image is provided by selective exposure of aphotosensitive photographic emulsion, generally containing theaforementioned photoresponsive silver halide crystals or the like. Thethus-produced latent image is developed, to provide a visible silverimage, by a suitable contact with any of the photographic developingsolutions set forth in the art. For the purpose of enhancing theresultant visible image's stability, the image may be suitably fixed,according to the procedures also well known to those skilled in the art.The resultant image-containing element may be then directly employed or,optionally, may be employed, where applicable, as a negative ima'ge, forexample, to provide a reversed or positive image by conventional contactor projection printing processes employing suitable photosensitiveprinting papers.

In the conventional photographic subtractive color processes which findextensive commercial utilization, color coupling techniques aregenerally employed to provide the requisite number of registered colorimages necessary for monochromatic and multichromatic reproduction.According to these techniques, one or more selectively photoresponsive,generally gelatinous, silver halide strata are selectively exposed toprovide .latent image record formation corresponding to the chromaticityof the selected subject matter. The resultant latent images are suitablydeveloped by selective intimate contact between one or more colordeveloping agents and one or more color formers or couplers to providethe requisite negative color images. Alternatively, the latent imagesare developed to provide visible silver images; the resultant visibleimages removed; the remaining residual silver halide exposed, and thesecond-formed exposure records developed by selective contact betweenone or more color developing agents and one or more color formers orcouplers, in the presence of exposed silver halide to provide thedesired colored positive image.

In diffusion transfer processes, for the formation of positive silverimages, a latent image contained in an exposed, photosensitive,generally gelatinous, silver halide emulsion is developed and,substantially contemporaneous with development, a soluble silver complexis obtained by reaction of a silver halide solvent with the unexposedand undeveloped silver halide of the emulsion. The resultant solublesilver complex is, at least in part, transported in the direction of asuitable print-receiving element, and the silver of the complexprecipitated in such element to provide the requisite positive imagedefinition.

Additive color reproduction may be produced by exposing a photosensitivesilver halide emulsion through an additive color screen having filtermedia or screen elements, each of an individual additive color such asred, blue or green, and by viewing the resultant image, subsequent todevelopment, through the same orla similar screen element.Alternatively, the photosensitive element may be employed to provide asilver transfer image analogous to the preceding description ofdiffusion transfer processing and the resultant transfer image may beviewed through the same, or a similar, additive color screen which issuitably registered with the silver transfer image carried by theprint-receiving image.

Subtractive color reproduction may be provided by diffusion transfertechniques wherein one or more photoresponsive spectrally selectivesilver halide elements, having an appropriate subtractivecolor-providing material associated therewith, are selectively exposedto provide the requisite latent image record formations corresponding tothe chromaticity of the selected subject matter and wherein thedistribution of colorproviding materials, by diffusion, to a suitableimagereceiving element, is controlled, imagewise, as a function of therespective latent image record formations.

The photoresponsive crystals of the present invention may also beemployed as the photoconductive component of electrophotographicmaterials, for example, inorganic photoconductive crystals such as zincoxide, selenium, cadmium sulfide, cadmium telluride, indium oxide,antimony trisulfide, and the like, and organic photoconductive crystalssuch as anthracene, sulfur, benzidine, the aromatic furanes of U.S. Pat.No. 3,140,946, and the like, as described in U.S. Pat. Nos. 2,987,395;3,047,384; 3,052,540; 3,069,365; 3,110,591; 3,121,008; 3,125,447; and3,128,179.

In preparing photoconductive layers, it is the usual practice to suspendthe photoconductive crystal in a suitable solvent in the presence of anelectrically insulating binder and then to dissolve the opticalsensitizing dye in this composition prior to coating on a conductingsupport. Where the layers are thus prepared, the optical sensitizingcomponents are added to the coating composition, prior to coating, inthe manner of the instant invention as described hereinbefore.

Alternatively, an unsensitized photoconductive layer can be prepared andthe coating then sensitized according to the previously describedalternate procedure.

Preferred binders for use in preparing the photoconductive layerscomprise polymers having fairly high dielectric strength and which aregood electrically insulating film-forming vehicles. Materials of thistype comprise styrene-butadiene copolymers; silicone resins;styrene-alkyd resins; soya-alkyd resins; poly(vinyl chloride);poly(vinylidene chloride); vinylidene chloride, acrylonitrilecopolymers; poly(vinyl acetate); vinyl acetate, vinyl chloridecopolymers; poly(vinyl acetals), such as poly(vinyl butyral);polyacrylic and methacrylic esters, such as poly(methyl methacrylate'),poly(n-butyl methacrylate, poly(isobutyl methacrylate), etc.;polystyrene; nitrated polystyrene; polymethylstyrene; isobutylenepolymers; polyesters, such as poly(ethylene-alkaryloxy-alkyleneterephthalate); phenolformaldehyde resins; ketone resins; polyamides;polycarbonates, etc. Methods of making resins of this type have beendescribed in the prior art, for example, styrene-alkyd resins can beprepared according to the method described in U.S. Pat. Nos. 2,361,019and 2,258,423. Other types of binders which can be used in thephotoconductive layers include such materials as paraffin, mineralwaxes, and the like.

Solvents of choice for preparing the last-mentioned coating compositionscan include a number of solvents such as benzene, toluene, acetone,2-butanone, chlorinated hydrocarbons, e.g., methylene chloride, ethylenechloride, etc., ethers, e.g., tetrahydrofuran, or mixtures of thesesolvents, etc.

The photoconductive layers can then be coated on a conducting support inany well-known manner such as the conventional doctor-blade coating,swirling, dipcoating, and the like, techniques. Although photoconductivelayers in some cases do not require a binder, it is usually beneficialto include some binder in a coating composition of this type, forexample, as little as 1 weight percent.

In preparing the coating composition, useful results will be obtainedwhere the photoconductor substance is present in an amount equal to atleast about 1 weight percent of the coating composition. The upper limitin the amount of photoconductor substance present is not critical. Asindicated previously, the polymeric materials in many cases do notrequire abinder in order to obtain a self-supporting coating on thesupport. In those cases where a binder is employed, it is normallydesired that the photoconductive substance be present in an amount fromabout 1 weight percent of the coating composition to about 99 weightpercent of the coating composition. A preferred weight range for thephotoconductor substance in the coating composition is from weightpercent to about 60 weight percent.

Coating thicknesses of the photoconductive composition on a support canvary widely. Normally a wet coating in the range from about 0.001 inchto about 0.01 inch is useful. A preferred range of wet coating thicknessmay be found to be in the range from about 0.002 inch to about 0.006inch.

Suitable supporting materials for the photoconductive layers of thepresent invention can include any of the electrically conductingsupports, for example, paper (at a relative humidity above percent);aluminum-paper laminates; metal foils, such as aluminum foil, zinc foil,etc.; metal plates, such as aluminum, copper, zinc, brass, andgalvanized plates, regenerated cellulose and cellulose derivatives;certain polyesters and especially thosehaving a thin electroconductivelayer (e.g., cuprous iodide) coated thereon; and the like.

The photoconductive elements can be employed in any of the well-knownelectrophotographic processes I which require photoconductive layers.One such process is the xerographic process. In a process of this type,the electrophotographic element is given a blanity of the layer in thedark. The electrostatic charge formed on the surface of thephotoconducting layer is then selectively dissipated from the surface ofthe layer by exposure to light through a negative by a conventionalexposure operation such as, for example, by a contact-printingtechnique, or by lens projection of an image, etc., to form a latentimage in the photoconductive layer. By exposure of the surface in thismanner, a charged pattern is created by virtue of the fact that lightcauses the charge to leak away in proportion to the intensity of theillumination in a particular area. The charge pattern remaining afterexposure is then developed, i.e., rendered visible, by treatment with amedium comprising electrostatically attractable particles having opticaldensity. The developing electrostatically attractable particles can bein the form of a dust, i.e., powder, a pigment in a resinous carrier,i.e., toner, or a liquid developer may be used in which the developingparticles are carried in an electrically insulating liquid carrier.Methods of development of this type are widely known and have beendescribed in the patent literature in such patents, for example, as U.S.Pat. No. 2,296,691, and the like. In process of electrophotographicreproduction such as in xerography, by selecting a developing particlewhich has as one of its components, a low-melting resin, it is possibleto treat the developed photoconductive material with heat and cause thepowder to adhere permanently to the surface of the photoconductivelayer. In other cases, a transfer of the image formed on thephotoconductive layer can be made to a second support which would thenbecome the final print. Techniques of the type indicated are well knownin the art and have been described inU.S. Pat. Nos. 2,297,691 and2,551,582 and in RCA Review, Vol. 15 (1954), pages 469-484. i

Since certain changes may be made in the above product and processwithout departing from the scope of the invention herein involved, it isintended that all matter contained in the above description or shown inthe accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

Whatis claimed is:

1. A radiation recording photographic element comprising photosensitivesilver halide having associated lwherein L represents a methine group; mrepresents a [positive integer of from 1 to 3, inclusive; Z and Z, eachirepresents the nonmetallic atoms necessary tocom- 'plete a heterocyclicring system containing an azole or azine nucleus; R and R, eachrepresents a divalent acrylic or cyclic group; X represents aquaternary'ammonium, sulfonium or phosphonium group; Y represents a or aCOO group; and W represents an anion.

2. A radiation recording photographic element as deatoms necessary tocomplete a heterocyclic ring system 8. A radiation recordingphotographic element as defined in claim 6 wherein said cyanine dyecomprises a cyanine dye of the formula:

wherein Z and Z each represents the nonmetallic containing a thiazole,selenazole, oxazole, imidazole or pyridine nucleus; R and R eachrepresents a divalent (F1115 (/3115 aliphatic group comprising from oneto five carbon /N N\ C] atoms; R represents an alkyl group comprisingfrom LP Y/ one to five carbon atoms or an aromatic group commm prisingsix nuclear atoms; X represents a N*(R,,) N N group wherein each Rrepresents an alkyl group comgum (2:11,

prising from one to four carbon atoms; Y represents g rllucum a SO or aCOO' group; and W represents an anion. wherein W is an anion.

3. A radiation recording photographic element as de- A radiationrecording Photographic element as fined in claim 1 wherein said silverhalide comprises silfined in claim 6 wherein Said cyanine y comprises aver iodobromide or silver iodochlorobromide. cyanine y of the formula:

4. A radiation recording photographic element as des I S r a fined inclaim 1 wherein said photosensitive silver ha- [C2115 lide is disposedas a particulate dispersion in a polymeric matrix. t N

5. A radiation recording photographic element as defined in claim 4wherein said polymeric matrix comprises gelatin. 3 (Cum 6. A radiationrecording photographic element as dei fined in claim 1 wherein saidcyanine dye comprises a dye of the formula:

(CH2): (llz):

wherein W is an anion.

10. A radiation recording photographic element as defined in claim 6wherein said cyanine dye comprises "v' a cyanine dye of the formula:

I l 40 R7 R3 i wherein V and V, each represents oxygen, selenium, sulfuror Q R1 wherein W is an anion. l; 11. A radiation recording photographicelement as defined in claim 1 wherein said cyanine dye comprises whereinR represents an alkyl group comprising from a cyanine dye of theformula: one to five carbon atoms; 2., and Z, each comprises the 5nonmetallic atoms necessary to complete an annulated A benzene ornaphthalene ring; R represents a hydrogen, //\/g(. methyl or ethylgroup; W represents an anion; R and I J R each represents an alkylenegroup comprising from i; one to five carbon atoms; X represents a -N (R/N ((lmm wherein each R, represents an alkyl group comprising (Elma jfrom one to four carbon atoms; and Y represents a v t v -SO;,' or a -COOgroup. M

7. A radiation recording photographic element as defined in claim 6wherein said cyanine dye comprises a wherein wis an anion cyanine dye ofthe formula: k

2. A radiation recording photographic element as defined in claim 1wherein said cyanine dye comprises a dye of the formula:
 3. A radiationrecording photographic element as defined in claim 1 wherein said silverhalide comprises silver iodobromide or silver iodochlorobromide.
 4. Aradiation recording photographic element as defined in claim 1 whereinsaid photosensitive silver halide is disposed as a particulatedispersion in a polymeric matrix.
 5. A radiation recording photographicelement as defined in claim 4 wherein said polymeric matrix comprisesgelatin.
 6. A radiation recording photographic element as defined inclaim 1 wherein said cyanine dye comprises a dye of the formula:
 7. Aradiation recording photographic element as defined in claim 6 whereinsaid cyanine dye comprises a cyanine dye of the formula:
 8. A radiationrecording photographic element as defined in claim 6 wherein saidcyanine dye comprises a cyanine dye of the formula:
 9. A radiationrecording photographic element as defined in claim 6 wherein saidcyanine dye comprises a cyanine dye of the Formula:
 10. A radiationrecording photographic element as defined in claim 6 wherein saidcyanine dye comprises a cyanine dye of the formula:
 11. A radiationrecording photographic element as defined in claim 1 wherein saidcyanine dye comprises a cyanine dye of the formula: